1. Field of the Invention
The present invention relates to a method of manufacturing semiconductor devices, and more specifically, to such a semiconductor device manufacturing method capable of reducing manufacturing costs and improving the operating ratio of semiconductor manufacturing apparatuses.
2. Description of the Related Art
A deposition technology using sputtering has already been technically established and frequently used at the research level for the formation of thin films of Ru or RuO2, which are candidates for the next generation DRAM capacitor electrodes. However, this technology is defective in the ability of covering stepped portions (hereinafter called xe2x80x9cstep covering abilityxe2x80x9d), and hence a thermal CVD method having a superior step covering ability is preferred for mass production processes and has been actively developed.
In the thermal CVD method, deposition raw materials are generally in the form of a liquid of an organic metal, a solution with a powder of an organic metal dissolved in a solvent or the like, these materials being vaporized by means of an vaporizer or bubbling and supplied to a substrate. Here, note that bisethyl-cyclopentadienyl-ruthenium (Ru(C2H5C5H4)2) is referred to as such a raw material.
However, in cases where films of bisethyl-cyclopentadienyl-ruthenium are formed on a substrate by means of a thermal CVD method of instance, films of Ru or RuO2 are deposited on members around the substrate such as, for instance, a substrate holder, and when the deposition process is continued, there would be a problem in that these films peel off, resulting in the formation of particles on the substrate and hence in a reduction in the manufacturing yield. In addition, when particles are generated, it is necessary to stop the operation of the semiconductor manufacturing apparatus for replacement of damaged component elements with new ones, and perform wet cleaning or the like. As a result, there arises another problem in that the operating ratio of the apparatus decreases to reduce productivity.
In order to cope with the above problems, it is necessary to clean a reaction chamber of the semiconductor manufacturing apparatus and remove the films deposited on the inner surface of the reaction chamber. There are methods of cleaning the films of Ru or RuO2 deposited on the inner surface of the reaction chamber including a dry cleaning method and a wet cleaning method. The dry cleaning method includes, for example, a plasma etching technique using oxygen and a chlorine gas as disclosed in Japanese Patent Application Laid-Open No. Hei 8-78396, and another plasma etching technique using a CIF3 gas as disclosed in Japanese Patent Application Laid-Open No. 2000-58529. However, the former technique is disadvantageous in that the etching rate for the Ru films is low, thus prolonging the etching time required to remove the films of a thickness on the order of xcexcm deposited on the reaction chamber. In addition, there is a drawback common to the former and latter methods in that adding a plasma function to a thermal CVD apparatus increases the manufacturing cost thereof. On the other hand, the wet cleaning method is disadvantageous in that it is necessary to open the reaction chamber to the atmosphere, thus prolonging the time required for sufficiently heating and cooling the interior of the reaction chamber with the result that the operating ratio of the apparatus is accordingly decreased. Moreover, a method of stopping the operation of the manufacturing apparatus and replacing the component members thereof on which the films are deposited with new ones involves the similar drawbacks as referred to above.
Accordingly, the object of the present invention is to provide a method of manufacturing semiconductor devices which is capable of reducing the manufacturing costs for semiconductor devices, as well as improving the operating ratio of a semiconductor manufacturing apparatus.
Bearing the above object in mind, according to a first aspect of the present invention, there is provided a method of manufacturing semiconductor devices comprising: a deposition process for forming a film containing Ru on a substrate in a reaction chamber; and a cleaning process for supplying a CIF3 gas to the reaction chamber so as to remove films, which were deposited on an inner surface of the reaction chamber in the deposition process, through thermochemical reactions.
According to this method, the manufacturing costs can be reduced, and the operating ratio of a manufacturing apparatus as used for implementing this method can be improved.
In a preferred form of the first aspect of the present invention, removing the films deposited on an inner surface of the reaction chamber in the cleaning process is carried out at a temperature ranging from 300xc2x0 C. to 500xc2x0 C. and at a pressure ranging from 665 Pa to 6650 Pa.
Thus, it is possible to further reduce the manufacturing costs as well as further improve the operating ratio of the manufacturing apparatus.
According to a second aspect of the present invention, there is provided a method of manufacturing semiconductor devices comprising: a deposition process for forming a film containing Ru on a substrate in a reaction chamber at a prescribed temperature; and a cleaning process for supplying a CIF3 gas to the reaction chamber at a temperature substantially equal to the temperature in the deposition process so as to remove films, which were deposited on an inner surface of the reaction chamber in the deposition process.
According to this method, it is not necessary to change the temperature in the reaction chamber in the course of from the cleaning process to the deposition process, and subsequently from the deposition process to the next cleaning process. This serves to improve the operating ratio of a manufacturing apparatus as used for implementing this method.
In a preferred form of the second aspect of the present invention, the pressure in the reaction chamber is made higher in the cleaning process than in the deposition process.
Thus, the etching rate of the Ru films can be further improved while maintaining the temperature in the cleaning process equal to the temperature in the deposition process. This serves to shorten the cleaning time, and improve the manufacturing efficiency as well.
In a preferred form of the third aspect of the present invention, the films deposited on an inner surface of said reaction chamber is removed in said cleaning process, through thermochemical reactions.
The above and other objects, features and advantages of the present invention will become more readily apparent to those skilled in the art from the following detailed description of preferred embodiments of the present invention taken in conjunction with the accompanying drawings.